Furnace



NOV 1949. G. R. SYLVESTER 1 2,485,506

FURNACE Filed May 6, 1946 e Sheets-Sheet 1 INVENTOR. GEORGERSYLVESTER1-? 1 .w L. I B H- ELIS D ATTORNEYS Nov 1, 194-9. s v s 2,486,506

FURNACE GSheets-Sheet 2 Filed May 6, 1946 INVENTOR.

GEORGE R.SYLVESTER MMMM ATTORNEYS Nov 1, 1949. G. R. SYLVESTER FURNACE 6Shets-Sheet 3 Filed May 6, 1946 INVENTOR.

GEORGE R.SYLVESTER MQ CWM' ATTORNEYS Nov 1, 1949. G. R. SYLVESTERFURNACE Filed May 6, 1946 6 Sheets-Sheet 4 INVENTOR.

GEORGE R.SYLVE STER m trim ATTORNEYS Nov 1, 1949. I s v s 2,486,506

FURNACE Filed May 6, 1946 6 Sheets-Sheet 5 INVENTOR. GEORGE R.SYLV ESTERATTORNEYS Nov 1, 1949.

G. R. SYLVESTER FURNACE Filed May 6, 1946 6 Sheets-Sheet 6 INVENTOR.GEORGE R. SYLVESTER VIM ATTORNEYS.

Patented Nov. 1, 1949 UNITED STATES PATENT OFFICE This invention relatesas indicated to furnaces and more especially to heat treating furnacesof the type adapted to maintain a work piece at an elevated temperaturefor a predetermined length of time, which furnaces are usually providedwith means whereby the work piece may be cooled at a controlled rate. 7

It is a principal object of my invention to provide a furnace of thecharacter described which is particularly adapted to be used for thetreatment of work pieces which require that there be a fluid lineconnected to the work piece during the heat treating operation althoughfrom the ensuing description of my invention it will be observed thatthe novel furnace is of general utility.

It is a further and more particular object of my invention to provide afurnace of the character described which is continuous in its operation,i. e. the furnace may be utilized as one component in a continuousproduction line.

It is a further object of my invention to provide a furnace in which thevarious controls over and connections with the work piece during theheat treating operation may be accomplished with a minimum of labor andby apparatus which is not only of simple and economical construction butwhich may be operated economically and with little likelihood of suchmoving parts as are associated therewith becoming deranged.

Other and more specific objects of my invention will appear as thedescription proceeds.

To the accomplishment of the foregoing and related ends, said inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description and the annexeddrawings setting forth in detail certain illustrative embodiments of theinvention, these being indicative, however, of but a few of the variousways in which the principle of the invention may be employed.

In said annexed drawings:

Fig. l is a plan view partially in section of a furnace constructed inaccordance with the principles of my invention;

Fig. 2 is a section view of the furnace illustrated in Fig. 1 taken on aplane indicated by the line. 22;

Fig. 3 is a view similar to Fig. 2 but showing only a portion of thefurnace at a different crosssectional plane from that on which Fig. 2vis: taken;

Fig. 4 is an enlarged side elevational view of the lower end of thefurnace as illustrated in Fig. 2;

Fig. 5 is a view of the apparatus illustrated in Fig. 4 taken on a planeat right angles to the plane of Fig. 4;

Fig. 6 is an enlarged part sectional, part side elevational view of theupper end of the mast in the center of the furnace as illustrated inFig. 2;

Fig. 7 is a fragmentary sectional view of a portion of such mast showingone of the electrical slip rings of such mast;

Fig. 8 is a diagrammatic View of a furnace incorporating the principlesof my invention by bein arranged for straight-line movement rather thanthe circular movement illustrated in Fig. 1-;

Fig. 9 is a view of a furnace somewhat similar to Fig. 8;

Fig. 10 is a sectional view of the heating zone of a furnace similar tothat of Fig. 2 except that provision is made for placing a plurality ofworkpieces at each station of the hearth and that the heating elementsare disposed vertically along opposite sides of the hearth instead ofhorizontally above as in Fig. 2

Fig. 11 is a plan view of the portion of the furnace shown in Fig. 10showing a portion of the rotating hood and the stationary hearth;

Figs. 12 and 13 are sectional views respectively of the heating zone andcooling zone of a modified form of furnace taken along a planecorresponding to that through which Fig. 2 was.

taken;

Fig. 14 is a sectional view of the furnace of Figs. 12 and 13 takenalong a plane through the loading and unloading zone thereof; and

Fig. 15 is a plan view of a portion of the hood and hearth of thefurnace illustrated in Figs. 12-14.

Referring now more specifically to the drawings and more especially toFigs. 1 and 2. the furnace here illustrated as embodying the principlesof my invention comprises as its principal features a stationary hearthI and a rotary hood 2. The hearth l in the form of constructionillustrated in Figs. 1 to 7 is annular in form, is made of suitablerefractory material, and supported at an elevation above the floor levelby means of spaced standards 3 forming a part of a supporting framework.

The hood 2 is built up of appropriate sections of refractory materialall maintained in assembled relation within a metallic framework whichincludes the vertically extendin legs 4 and annular brackets 5 carriedby the bottom ends of such legs which brackets rest on wheels 6 by whichthe entire hood is rotatably supported on rails I.

While the hearth l is in the form of a full and continuous annulus, thehood, while annular in form, has a segmental portion omitted asillustrated in Fig. 1 between the five and seven oclock positions. Thus,as the hood 2 is rotated about the vertical axis of the furnace, thehearth I will be progressively uncovered to make possible the chargingand unloading of the furnace.

In the preferred embodiment of my invention the cross-section of thehood over the hearth is such as to closely confine the space above thehearth which is to be occupied by the work pieces. The hearth ispreferably provided in circumferential spaced points with radially andupwardly extending partitions 8 which substantially span the spacewithin the hood over the hearth. As most clearly illustrated in Fig. 1,the hood at preferably each of its open ends such as 9 is provided witha restricted throat which coincides in cross-section to substantiallythe size and shape of the partitions 8 and extending for a distanceequal at least to the space between one adjacent set of partitions sothat the space within the hood is at all times substantially sealed fromthe atmosphere as the hood is rotated over the hearth.

A seal between the lower edges of the hood and the hearth is provided bymeans of annular brackets II! which extend into a sand trap I I carriedby annular brackets I2 on opposite sides of the supporting framework 3.

Axial alignment about a vertical aXis between the hearth and the hood isinsured by the provision of annular rails I3 on the inner and outersurfaces of the supporting structure 3 and with which rails rollers I4carried by the brackets 5 are in engagement.

As previously indicated the heat treating furnace of my invention isparticularly adapted for operation on devices which require a fluidconnection thereto during the heat treating operation. A representativeexample of such a work piece is an evaporator used in conventionalrefrigerators. Best results can be secured in the fabrication of suchevaporators if, durin the brazing operation performed by the heattreating furnace of my invention, the space within the evaporator isalternately maintained at subatmospheric or atmospheric andsuper-atmospheric pressures. This is accomplished by having a pipe suchas I5 extend upwardly through the hearth at each work piece station sothat the work piece may be connected to the upper end of the pipe by anyconventional connection means which it is believed unnecessary to moreparticularly describe herein. The lower end of each of the pipes I5 isconnected to conduits I6 and I! which are respectively controlled bymeans of valves I8 and I9. The valves l8 and I9 are preferably springloaded so that in their normal state they are closed. Various forms ofvalves capable of performin this function and constructed as aboveexplained are available on the market and will, therefore, not bedescribed in greater detail.

The valves I8 and I9 are conveniently actuated at the appropriate timeduring the heat treating cycle by means of cam tracks 28 and 2irespectively, which cam tracks are carried on the lower ends of brackets22 and 23 depending fromthe main framework 4 of the hood. Thus, ifduring the first predetermined interval during the heat treating cycle apartial vacuum is to be maintained in the work piece, the hood will havemounted thereon adjacent its forward end a cam track which will depressand open the valve in the line leading to a vacuum connection, and atthe conclusion of that heat treating interval such valve will then beclosed by an elevation in the contour "of the aligned cam track and airor other gas under atmospheric or superatmospheric pressure introducedto the interior of the article being treated by a similar actuation ofthe other valve by means of a similar cam track.

The lower end of the pipe I5 passes through a bracket 24. Around thepipe I5 is a spring 25 which bears at one end on the elbow or otherprojection on the lower end of the pipe I5, and at its upper end bearson the bracket 24 so as to urge the pipe I5 downwardly. This expedientinsures that when the pipe I 5 is connected to the work piece the latterwill be held in position on the hearth. The provision of such springalso makes possible the utilization of a connecting means between thepipe I5 and the work piece which relies upon spring tension to maintaina seal.

A furnace constructed in accordance with my invention makes possible theprovision of separate heatin and cooling zones in the following manner:

In the heating zone the hood caries in the space above the hearth, asviewed in the lefthand portion of Fig. 2, a plurality of resistance orother heating elements 26 such as hot oil or gas which may be connectedby means of a lead such as 2'1 to a sli ring assembly S, theconstruction of which will be explained in greater detail at a laterpoint. I

In the cooling zone the hood will carry a cooling or heat exchange coilgenerally indicated at 28 through which cooling water for example may becirculated by being introduced thereto through the pipe 28 anddischarged therefrom through the pipe 29. The pipe 28 is connected tothe mast 30 by means of a slip connection T, the construction of whichwill be explained at .t. a later point. In order to insure rapidcirculation of air through the cooling zone in the furnace the hoodadjacent the coolin zone may be provided with a circulating fangenerally indicated at 1-H which is driven by means of a motor 32. Themotor 32 is energized electrically by means of a lead 33 connected toanother slip ring device S on the mast 30.

It will be observed that the effluent from the cooling coil 28 throughthe pipe 29 is discharged into an open ditch at the center of thefurnace and drained to 'a suitable catch basin not shown.

The hood is rotated with respect to the hearth by means of an electricmotor such as 34 carried by the hearth frame and connected to one of thewheels 6 by means of a cross-shaft 35 and a sprocket chain 36. The motor34 may be energized from the same lead 33 which is utilized to energizethe fan motor 32.

The slip connection S previously described is illustrated in Fig. '7 andcomprises a stationary part 31 rotatably supported by means ofantifriction bearings 38 on a radially outwardly extending flange 39 onthe mast 30. The mast 30 has secured thereto radially extending arms 40which at their inner ends are connected to an electrical lead such as 4|and at the outer ends carry a contact wheel 42 which is in engagementwith an annular" ring 43 of conductive material to which one side of thelead 33 is connected.

The other side of the lead 33 is connected to a similar ring 44 withwhich another arm 45 is in communication through a wheel 46,

The slip connection T by means of which fluid is introduced to theconduit 28 comprises a stuff- .ing box generally indicated at 41 mountedon the upper end of the mast 30 and into which projects a stationarysleeve 48. The sleeve 48 is connected in any suitable fashion to anelbow 49 or other part of the pipe 28.

As viewed in Fig. 1 and as previously explained during the normaloperation of my furnace, the loading and discharging station progressesaround the stationary hearth I. In order to facilitate charging andunloading the furnace, I provide a platform 50 which is carried on thetrack I and carried along with the hood by means of a, bracket 52connected to the hood framework. The operator whose duties are to chargeand unload the furnace will stand on the platform 50 and be carriedaround the furnace with the hearth and thus the operator will always bepositioned at the charging and unloading station.v The treated anduntreated work pieces are taken away from and brought to the movingoperators station by means of a suitable crane such as 53 which operateson a circular track 54 arranged concentric with the axis of the furnace.

While in the preferred embodiment of my invention the hearth and hoodare circular, thus making possible the utilization of the furnace as anelement of a continuous production line, nevertheless these sameobjectives may be achieved in a measure at least by an arrangement suchas that illustrated in Fig. 8 in which the hearth 55 is arranged on astraight line and the hood 56 is arranged for straight line travelrelatively to the stationary hearth. In this modification of theinvention the hood is provided with a heating zone generally indicatedat 51 and a cooling zone generally indicated at 58. The general design,construction, and mode of actuation of the hearth, hood and associatedmechanism as illustrated in Fig. 8 is similar to that illustrated anddescribed in Figs. 1 to '7 except that the parts instead of beingcircular and endless are arranged in a straight line. In the form ofconstruction illustrated in Fig. 8 the normal operation of the hoodduring the heat treatment of the work pieces is from right to left at arate determined usually by the length of the hood heating and coolingsections and the time during which the heat treating operation need becarried out. After the hood has completed its travel at thispredetermined speed from the extreme right-hand end to the extremeleft-hand end, then the carriage carrying the hood is quickly returnedto the right-hand end of the structure and the sequence repeated.

When it is not necessary to provide controlled cooling of the workpieces then an arrangement illustrated in Fig. 9 may be employed whichis generally similar to that illustrated in Fig. 8 with the exceptionthat the controlled cooling zone is omitted. When this type of structureis employed then the heat treating operation may be carried out duringboth directions of travel of the hood with respect to the stationaryhearth.

Insofar as the parts in the modified furnaces of Figs. 10 and 11 andFigs. 12-15 are the same or similar as those in Figs. 1-'-'7, likenumerals have been used and the prior description is applicable exceptas hereinafter noted.

The furnace shown in Figs. 10 and 11 is the same as that of Figs. 1'!except that provision is made for treating several workpiecessimultaneously in each of the sections defined by the partitions 8. Thisis accomplished by providing a plurality of shelves 59 and a pluralityof pipes [5, one pipe I5 being associated with each shelf. The pipes l5are adapted to carry a fluid pressure medium pulsated in the same manneras in the form of furnace illustrated in Figs. l-"l. In order to providea more uniform heat distribution, the heating elements 26 are disposedvertically on opposite sides of the shelves 59 rather than beinghorizontally disposed above a single workpiece as in the left-handportion of Fig. 2.

In the 'modified furnace illustrated in Figs. 12-15 there are pluralshelves 59 and plural pipes l5 and vertically disposed heating elements26 as in Figs. 10 and 11, but there is in addition a pipe 60' extendedupward through the hearth I controlled by a valve l9. The purpose ofsuch pipe 60 is to permit carrying on of the heat treating operation ina controlled or neutral atmosphere by supplying to the space around thehearth a suitable inert gas. Such valve controlled pipe 60 may also beused in the furnaces illustrated in Figs. l-11 whether or not there areany pipes l5 connected to workpieces. That is to say that my furnacesare not limited to use in treating refrigerator evaporators or the likebut are readily usable in treating all kinds of articles. As a matter offact, the inert gas may be piped into the treating chamber through pipes[5 rather than providing separate pipes 60.

I It is also to be noted that in the furnace of Figs. 12-15, the wheels6 are grooved whereby the rails l3 and rollers l4 shown in Fig. 2 may bedispensed with, sufi'iciently accurate alignment between the hearth andhood being attained through the grooved wheels 6.

In the furnace of Figs. 12-15 instead of employing partitions 8 on thehearth, separate hoods 62 are employed, each having its open bottom endseated in a, sand trap 6|. Each hood can be lifted upwardly to unloadand charge the hearth and then lowered prior to the hood 2 rotating to aposition to enclose the same. For convenience in lifting and. loweringthe hoods 62, an overhead circular rail 63 which is concentric to thehood 2 movably carries several chain and pulley hoists 64, the chainportion of which can be quickly hooked to the top of any hood 62 whichit is desired to lift. Another difference in this furnace is theparticular construction of the cooling zone in which, as shown in Fig.13, the blower 3| is disposed centrally above the hood 62 and the cooledair which is drawn through the cooling coil 28' is forced downwardly andis diverted down opposite sides of each hood 62 and the heated air isdrawn up through spaces on opposite sides of the hood 2 as shown by thearrows in Fig. 13.

While not shown in the drawings, it is contemplated that instead of thepartitions 8 or the hoods 6 2, the hood 2 may be provided with avertically slidab'le door at each open end thereof and between theheating and cooling zones thereof. In such a furnace the hood 2, insteadof being moved at a uniform rate of speed, could be indexed ratherrapidly from one position to the next and raising such doors to clearthe workpieces during such indexing. The hood 2 can be indexed onesection at a time or, if desired, it can be indexed the entire number ofsections between the ends thereof.

Other modes of applying the principle of the invention may be employed,change being made as regards the details describe-d, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

I, therefore, particularly point out and distinctly claim as myinvention:

1. In a heat treating furnace, the combination of a hearth forsupporting a hollow workpiece to be treated, a hood enclosing a portionof the longitudinal extent of said hearth, a fluid conduit on saidhearth for connection with the workpiece, a valve controlling the fluidsupply into the workpiece through said conduit, means for moving saidhearth and hood longitudinally relative to one another to expose theworkpiece and means on said hood cooperatively engaging said valve forclosing said valve during such exposure,

2. In a heat treating furnace, the combina tion of a hearth forsupporting a workpiece to be treated, a hood enclosing a portion of thelongitudinal extent of said hearth and defining therewith a workpiecetreating zone, a fluid conduit on said hearth, and a valve controllingthe fluid supply into such treating zone, said hearth and said hoodbeing longitudinally movable relative to one anotherto progressivelyexpose a portion of said zone to permit unloading of workpiecestherefrom, and said hood including cam means engageable with said valvefor closing said valve during such exposure.

3. In a heat treating furnace, the combination of a stationary hearthupon which a plurality of separate hollow :work pieces are adapted to besupported in spaced relation longitudinally thereof, fluid conduit meanson said hearth for connection with said work pieces, separate valvesrespectively controlling the fluid supply into the work pieces throughsaid conduit means, vertically extending battles on said hearth betweenthe work stations thereon, a hood having a longitudinal extent less thansaid hearth and laterally enclosing that portion of the hearth to whichit is adjacent, said hood divided into different treating zoneslongitudinally thereof and having a restricted throat at at least oneend thereof, said throat having a cross-section substantially the sameas the size of said bafiies and a longitudinal extent equal to at leastthe distance between adjacent baflles, temperature modifying means ineach of the zones of said hood, means for moving said hood along saidhearth, and cam means on said hood engageable with said valves foroperating the same during movement of said hood.

4. In a heat treating furnace, the combination of a stationary hearthupon which a plurality of separate hollow work pieces are adapted to besupported in spaced relation longitudinally thereof, fluid conduit meanson said hearth for connection with said work pieces, separate valvesrespectively controlling the fluid supply into the work pieces throughsaid conduit means, vertically extending bafiles on said hearth betweenthe work stations thereon, a hood having a longitudinal extent less thansaid hearth and laterally enclosing that portion of the hearth to whichit is adjacent, said hood divided into different treating zoneslongitudinally thereof and having a restricted throat at at least endthereof, said throat having a cross-section substantially the same asthe size of said bafiies and a longitudinal extent equal to at least thedistance between adjacent baiiles, temperature modifying means in eachof the zones of said hood, means for moving said hood along said hearth,and means carried by said hood for progressively actuating said valvesas said hood moves along said hearth.

5. In a heat treating furnace, the combination of a circular stationaryhearth upon which a plurality of separate hollow work pieces are adaptedto be supported in spaced relation circumferentially thereof, fluidconduit means on said hearth for connection with said work pieces,separate valves respectively controlling the fluid supply into the Workpieces through said conduit means, radially and vertically extendingbaffles on said hearth between the work stations thereon, a part-annularhood having a circumferential extent less than said hearth and laterallyenclosing that portion of the hearth to which it is adjacent, said hooddivided into different circumferentially adjacent treating zones andhaving a restricted throat at at least one end thereof, said throathaving a cross-section substantially the same as the size of saidbafiies and a circumferential extent equal to at least the distancebetween adjacent bafiles, temperature modifying means in each of thezones of said hood, means for progressively moving said hood around oversaid hearth, and means carried by said hood for progressively actuatingsaid valves as said hood moves around said hearth.

6. In a heat treating furnace, the combination of a stationary annularhearth for supporting a hollow workpiece to be treated, a hood enclosinga portion of the longitudinal extent of said hearth and definingtherewith a workpiece treating zone, a fluid conduit on said hearth forconnection with the workpiece, valves connected to sources of fluid atdifierent pressures and selectively actuatable to supply fluid into theworkpiece through said conduit, means for moving said hood relative tosaid hearth, and means carried by said hood for alternately actuatingsaid valves as said hood moves around the portion of said hearth onwhich the workpiece is supported.

7. In a heat treating furnace, the combination of a stationary annularhearth for supporting a hollow workpiece to be treated, a hood enclosinga portion of the longitudinal extent of said hearth and definingtherewith a workpiece treating zone, a fluid conduit on said hearth forconnection with the workpiece, valves connected to sources of fluid atdifierent pressures and selectively actuatable to supply fluid into theworkpiece through said conduit, means for moving said hood relative tosaid hearth, and means carried by said hood for alternately actuatingsaid valves as said hood moves around the portion of said hearth onwhich the workpiece is supported and for simultaneously closing saidvalves when said hood moves to expose the portion of said hearth onwhich the workpiece is supported.

8. In a heat treating furnace, the combination of a hearth forsupporting a workpiece to be treated, a hood enclosing a portion of thelongitudinal extent of said hearth, a fluid conduit on said hearth forconnection with the workpiece, a valve controlling the fluid supply tothe workpiece through said conduit, means for moving said hearth andhood longitudinally relative to one another to expose the workpiece,means for closing said valve during Slllch exposure, and spring meansassociated with said conduit operative to yieldably urge said conduitdownward and thereby yieldably press the workpiece to which it isconnected against said hearth.

GEORGE R. SYLVESTER. REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,749,866 Winzer Mar. 11, 19301,798,649 Bartling Mar. 31, 1931 1,809,727 Sanders June 9, 19311,903,909 Cope et al Apr. 18, 1933 2,015,699 Trainer et al Oct. 1, 19352,231,956 Schwier Feb. 18, 1941 2,296,791 Keener et al Sept. 22, 19422,417,063 Cooper Mar. 11, 1947 FOREIGN PATENTS Number Country Date273,894 Italy May 5, 1930

